Apparatus and method for avoiding unnecessary cuts by electronic yarn cleaners



" Nov. 4, 1969 E, FEUX 3,476,329

APPARATUS AND METHOD FOR AVOIDING UNNECESSARY CUTS BY ELECTRONIC YARN CLEANERS Filed June 14. 1966 3 Sheets-Sheet l uvvswron ERNST FEL/ x Nov. 4, 1969 E. FELIX 3,476,329

, APPARATUS AND METHOD FOR AVOIDING UNNECESSARY CUTS BY ELECTRONIC YARN CLEANERS Filed June 14, 1966 3 Sheets-Sheet 2 nwE/v'roF? ERNST F254 IX Nov. 4, 1969 E. FELIX 3,476,329

APPARATUS AND METHOD FOR AVOIDING UNNECESSARY CUTS BY ELECTRONIC YARN CLEANERS Filed June 14, 1966 3 Sheets-Sheet 5 .N'VEJ TOR. ERNST F E L /X United States Patent 3,476,329 APPARATUS AND METHOD FOR AVOIDING UNNECESSARY CUTS BY ELECTRONIC YARN CLEANERS Ernst Felix, Uster, Switzerland, assignor to Zellweger Ltd., Uster, Switzerland, a corporation of Switzerland Filed June 14, 1966, Ser. No. 557,483 Claims priority, application Switzerland, July 6, 1965, 9,481/ 65 Int. Cl. B65h 63/00; D02j 1/14; D01l1 13/22 US. Cl. 242-36 Claims ABSTRACT OF THE DISCLOSURE The signal which is produced in proportion to the yarn cross-section traveling through the measuring apparatus is carried to a switch stage which is regulated in sensitivity by the signal from the yarn speed discriminator produced in proportion to the yarn speed. The switch stage then produces an output signal in relation to the cross-section signal as modified by the sensitivity of the switch stage for activating the yarn cutter.

This invention relates to an apparatus and method for avoiding unnecessary cuts by electronic yarn cleaners. More particularly, this invention relates to an apparatus and method for avoiding unnecessary cuts by electronic yarn cleaners during running in of winding spindles.

Electronic yarn cleaners capable of removing coarse yarn from a traveling yarn usually locate the coarse yarn by producing an electric signal corresponding to the yarn cross section in a measuring apparatus through which the yarn travels. The signal is then passed through a low-pass filter in order to eliminate short periodic variations and pass on only a long periodic signal which char acterizes the coarse yarn. However, this requires a certain minimal traveling speed of the yarn at a given cutotf frequency of the low-pass filter. Thus, because the cross wound bobbin starts and runs out slowly, the yarn travels at a speed less than the minimal traveling speed so that short periodic signal variations due to short periodic variations in the cross section of the yarn are also passed by the low-pass filter. Therefore, since the amplitudes of short periodic variations of the signal are considerably greater than the amplitudes of long periodic variations, there is a rather great probability of occurrence during the starting and run out periods that a short periodic variation with an amplitude corresponding to the signal produced by a coarse yarn will pass through the low-pass filter. This results in unnecessary cutting of the yarn by the electronic yarn cleaner.

It is an object of the present invention to provide an electronic yarn cleaning apparatus and method which avoids the aforedescribed disadvantage of conventional electronic cleaners and avoids unnecessary cutting of the yarn during the starting and runout periods of the cleaner.

It is another object to provide an electronic yarn cleaning apparatus and method which produces an electric signal in dependence on the traveling speed of yarn to be spooled for regulating the sensitivity of the yarn cleaning apparatus and method.

Generally, the invention relates to an apparatus and method for avoiding unnecessary cutting of a traveling yarn by electronic yarn cutters in removing coarse sections of yarn. The invention measures the speed of a yarn during travel through an electronic yarn cleaner and regulates the sensitivity of the yarn cleaner in relation to the measured yarn speed. This results in the yarn cleaner cutting only the undesirable coarse sections of yarn from the traveling yarn as the signal amplitudes relating to the sections of yarn having short periodic variations in yarn cross section are prevented from bypassing the low-pass filter during starting and runout periods.

The invention is utilized with an electronic yarn cleaner having a measuring device for producing a signal proportional to the cross section of a yarn traveling through the cleaner, a switch stage for receiving the produced signal having elements for adjusting the sensitivity of the yarn cleaner to produce an output signal corresponding to excessive yarn cross sections and a cutting device for cutting the traveling yarn in response to the delivered signal exceeding a predetermined value. The invention includes a speed discriminator means for measuring the speed of the yarn traveling through the yarn cleaner which is operatively connected to the elements of the switch stage for regulating the elements in relation to the measured speed of the traveling yarn.

The speed of the yarn is measured by measuring the rotational speed of a bobbin spooling up the traveling yarn or by measuring the frequencies of the signal produced by the measuring device of the yarn cleaner.

These and other objects and advantages of the invention will become more apparent from the following detailed description and appended claims taken in conjunction with the accompanying drawings in which:

FIG. 1 illustrates a schematic of an electronic yarn cleaner incorporating the invention;

FIG. 2 illustrates a perspective view of one form of the invention wherein the rotational speed of a bobbin cam cylinder is measured;

FIG. 3 illustrates a circuit utilized in the structure shown in FIG. 2;

FIG. 4 illustrates a circut of a modification wherein the frequencies of the yarn measuring of the invention signal are measured;

FIG. 5 illustrates a circuit of another modification of the invention;

FIG. 6 illustrates a circuit of the switch stage and cutting device as connected to the measuring apparatus and speed discriminator of FIG. 1; and

FIG. 7 illustrates a circuit similar to FIG. 6 wherein the speed discriminator is operably connected to the measuring apparatus.

Referring to FIG. 1, as a yarn 1 travels through a conventional measuring apparatus 2 of an electronic yarn cleaner, an electric signal U proportional to the thickness of the yarn is produced by the measuring apparatus 2 in the conventional manner. The signal is then directed to a switch stage 3 comprising elements for adjusting the sensitivity of the yarn cleaner.

The switch stage 3 is connected to an output stage 4, such as, a cutting device, to deliver a signal thereto for instigating the cutting of the yarn when the measured thickness of the traveling yarn 1 is greater than desired. In addition, a speed discriminator 5 which measures the speed of the traveling yarn 1 is operatively connected to the elements of switch stage 3 which adjust the sensitivity of the yarn cleaner for regulating the elements.

Referring to FIGS. 2 and 3, a yarn speed discriminator 5 is controlled in response to the speed or r.p.m. of a cam cylinder 6 driving a bobbin 7 by a contact or switch mechanism 8 which is actuated, for example, by being closed, at least once for each revolution of the cam cylinder 6. The circuit of the discriminator includes a storage condenser 10 which is charged over a charging resistance 11 to an auxiliary voltage U when the contact 8 is open. When the contact 8 is intermittently closed during rotation of the cylinder 6, the circuit shorts and the charge accumulated in the condenser 10 is exhausted so that the voltage U collapses. The voltage U increases again when the switch 8 is opened. The shorter the sequence of the short circuit intervals at the switch 8 the lower is the voltage U A voltage U corresponding to the medium value of the voltage U is produced by means of a resistor 12 and a condenser 13 suitably arranged in the discriminator circuit. The voltage U which is relatively small at normal speeds of the cylinder 6 and which increases at starting up and running out of the cross wound bobbin 7, provides a signal to actuate the elements adjusting the sensitivity of the yarn cleaner in the conventional manner. This actuation may be continuous or stepwise whereby the voltage U actuates, for example, a level switch, known per se, Which controls the sensitivity of the yarn cleaner.

Alternatively, the speed of travel of the yarn can be transferred into an electric signal for the discriminator by measuring the rotational speed of the cross Wound bobbin 7 and feeding the measurement into the discriminator 5.

Another manner of forming an electric signal corresponding to the speed of travel of the yarn 1 is the direct use of the signal U As mentioned above the amplitudes of short periodic variations are considerably greater than those of the long periodic variations. Further, in most cases, the maximal amplitude of the signal corresponding to periodic variations of the thickness of the yarn is associated with a wave length of two to three times the staple length. Since the amplitude decreases considerably towards the short wave lengths, and since the amplitudes of the shorter periodic thickness variations are further reduced because of the finite length of the measuring field of the apparatus 2, the frequencies of a signal U which correspond to the periodic variations of the thickness of yarn with two to three times the staple length dominate. It is noted that a decrease of the amplitude of the periodic variations of the thickness of the yarn can also be observed at greater wave lengths. The signal or voltage U can therefore be fed to a frequency discriminator which produces a corresponding output signal in a conventional manner.

Referring to FIG. 4, the circuit of a velocity discriminator can be modified with a transistor 23 which is short circuited with a current flowing through a resistor 22 so that a voltage U, is zero in the state of rest. If a signal voltage U arrives at the base of the transistor 23 through a frequency-dependent resistance-condenser (RC) element comprising a condenser 20 and a resistor 21, the transistor 23 is at least partly opened whereby the voltage U slowly increases. When the travel velocity of the yarn is slow, the frequencies of U are low and the voltage U increases slowly. When the yarn travels at full speed, the frequencies of U are high so that the voltage U; increases at a considerable rate. The voltage U; can be made to act on the elements which adjust the sensitivity of the yarn cleaner.

However, a condition for functioning of the circuit shown in FIG. 4 is that the medium voltage U in the ranges for coarse and fine yarns remains equal within predetermined limits.

Referring to FIG. 5, another modified discriminator circuit may be used wherein this latter condition is not required, assuming that U is always high. In such a circuit a condenser 27 is connected to the collector of the transistor 23 over a diode 26 in order to prevent a great increase of the voltage U when starting and running up. Therefore, when the first pulses of U arrive, the condenser 27 is charged over a resistor 28 before the voltage U; increases noticeably. Advantageously, the charging time constant of the condenser 27 is chosen over the resistor 28 so that the increase of the voltage U, requires a time interval which is approximately equal to that required by the cam drum 6 for running up to normal operating speed of the yarnpassage.

As in the previously described embodiments, the pulsat ing voltage at the collector of the transistor 23 is also smoothed by means of a resistor 12 and a condenser 13.

Referring to FIG. 6, the signal U from the measuring apparatus 2 is conveyed through a capacitor to a potentiometer 31 in the switch stage 3. In addition, the output signal U U from the speed discriminator 5 is conducted to a terminal 30 of the switch stage 3 and fed over a resistor to the same terminal of the potentiometer as the signal U During operation, U represents an AC voltage which passes the coupling condenser whereas signals U or U respectively, represent DC voltages which give the bias for a transistor 32. This bias is adjustable by the potentiometer setting and controls, therefore, the sensitivity of the circuit. In operation, the voltage taken from the potentiometer 31 actuates a Schmitt-trigger of known construction which consists of the transistors 32, 33 with associated resistors. When the voltage U or U is small, the Schmitt-trigger is less sensitive than in the case when the voltage is higher. Similarly, the Schmitt-trigger is also less sensitive than the tap of the potentiometer 31 is in a lower or higher position. The output pulses from the Schmitt-trigger are fed through a blocking capacitor 34 to an output terminal 35 connected to the output stage 4.

The output stage 4 has an input terminal 40 which connects to the output terminal 35 of the switch stage 3. The pulses received from the switch stage 3 via the terminal 40 control a multivibrator of known construction with transistors 41, 42. A power stage in the output stage 4 having a transistor 43 is connected to a coil 44 in the electrical circuit of a cutter to energize the coil 44. In operation, upon being energized, the coil 44 attracts the armature 45 which in turn pushes the slider 46 of the cutter with the cutting edge against an abutment 47. Since the yarn 1 travels in a path between the cutting edge of the slider 46 and the abutment 47, the yarn 1 becomes severed upon energization of the coil 44. The cutter is of known construction, for example, as shown in US. Patent 3,322,013 and therefore is not further described.

Referring to FIG. 7, the circuit is similar to that shown in FIG. 6 and need not be further described. However, as shown, the speed discriminator S is supplied directly from the measuring apparatus 2 with the signal U The operation of the switch stage 3 and output stage 4 is similar to that described above in FIG. 6.

Having thus described the invention, it is not intended that it be so limited as changes may be readily made therein without departing from the scope of the invention. Accordingly, it is intended that the subject matter described above and shown in the drawings be interpreted as illustrative and not in a limiting sense.

What is claimed is:

1. In combination with an electronic yarn cleaner having a measuring device for producing a signal proportional to the cross section of a yarn traveling through the yarn cleaner, a switch stage for receiving the produced signal having elements for adjusting the sensitivity of the yarn cleaner to produce an output signal corresponding to excessive yarn cross sections and a cutting device for cutting the traveling yarn in response to the output signal, a speed discriminator means for measuring the speed of the yarn traveling through the yarn cleaner, said speed discriminator being operatively connected to the elements in the switch stage for regulating the elements to adjust the sensitivity of the yarn cleaner in relation to the measured speed of the traveling yarn whereby unnecessary cuts in the traveling yarn are avoided during run-up and run-down of the yarn.

2. The combination as set forth in claim 1 which further includes a rotatable bobbin for spooling up the traveling yarn, and a rotatable cam cylinder for rotating said bobbin, said speed discriminator means being operably connected to one of said bobbin and cam cylinder for actuating said speed discriminator means in response to the revolution of said one of said bobbin and cam cylinder.

3. The combination as set forth in claim 2 wherein said speed discriminator means includes an electrical circuit for producing a signal in response to the measured speed of the traveling yarn, said circuit having a switch mechanism operably connected to said cam cylinder for intermittent actuation in response to each revolution thereof, a storage condenser arranged in parallel with said switch mechanism for shorting the circuit upon closing of said switch to produce a voltage to regulate the elements of the switch stage and an auxiliary signal means for charging said condenser.

4. The combination as set forth in claim 1 wherein said discriminator means includes a circuit having a transistor for receiving the produced signal, a resistor for short circuiting said transistor, a frequency-dependent resistance-condenser element including a condenser and a second resistor for passing the produced signal to said transistor for at least partly opening said transistor to produce an increasing voltage output for regulating the elements of the switch stage in response to the frequencies of the produced signal.

5. The combination as set forth in claim 4 wherein said circuit further includes a series resistor and condenser means for obtaining the medium value of the voltage intermittently prevailing at said transistor for smoothing said voltage.

6. The combination as set forth in claim 5 wherein said circuit further includes a retarding means for preventing an excessive voltage output increase upon running up of the traveling yarn, said retarding means including a diode connected on one side to the collector of said transistor, a second condenser connected to the other side of said diode and a third resistor connected between said diode and second condenser for charging said second condenser.

7. A method of adjusting the sensitivity of'an electronic yarn cleaner for avoiding unnecessary cutting of a traveling yarn comprising the steps of measuring the speed of the traveling yarn through the electronic yarn cleaner, regulating the sensitivity of the electronic yarn cleaner in response to the measured speed of the traveling yarn whereby unnecessary cuts in the traveling yarn avoided during run-up and run-down of the yarn.

8. A method as set forth in claim 7 wherein said step of measuring the yarn speed includes measuring the rotational speed of a bobbin spooling up the traveling yarn which rotational speed is proportional to the yarn speed through the electronic yarn cleaner.

9. A method as set forth in claim 7 wherein said step of measuring the speed of traveling yarn includes producmg a signal proportional to the yarn cross section, and

determining the frequencies of said signal to produce an output signal in response to said determined frequen cies.

10. A method as set forth in claim 9 which further includes the step of smoothing said output signal.

References Cited UNITED STATES PATENTS 

